The present disclosure relates to a laminated chip device, and more particularly, to a laminated chip device in which at least two unit devices having different characteristics are combined in a single chip.
A resistor (R), a capacitor (C), and an inductor (L) are typical passive devices in an electronic circuit, and these typical passive devices have a great variety of functions and roles. For example, the resistor serves to control the flow of current flowing through a circuit and achieve an impedance matching in an alternating current circuit. Although the capacitor basically serves to cut off a direct current and pass an alternating current, the capacitor serves to constitute a time constant circuit, a time delay circuit, and RC and LC filter circuits, and the capacitor itself also serves to eliminate a noise. The inductor performs functions of eliminating a high-frequency noise, matching impedance, or the like.
Further, a varistor changes in resistance according to an applied voltage, and has thus been widely used as a protective device for protecting important electronic components and a circuit from an overvoltage (a surge voltage) and static electricity. That is, a current does not flow in the varistor under a normal condition; however, when an overvoltage exceeding a predetermined level of voltage is applied to both ends of the varistor, a resistance of the varistor drastically decreases to allow most current to flow through the varistor, so that the current does not flow in other devices, thereby protecting the circuit from the overvoltage. The varistor tends to be miniaturized and arrayed to protect a highly integrated circuit and the like from a static electricity and overvoltage according to miniaturization of electronic apparatuses.
Alternatively, at least two unit devices having different features from each other may be combined to form a single chip. For example, the varistor and the resistor may be combined to effectively protect important electronic components or circuits from the overvoltage. Also, combination of a varistor and an inductor, combination of a varistor and a capacitor, or combination of an inductor and a capacitor may eliminate a noise component to ensure the stable operation of the electric component or circuit.
As described above, in the case where at least two unit devices are combined in a single chip, the chip is manufactured by laminating a plurality of sheets in a vertical direction, and a conductor pattern such as an electrode to implement each device is formed on each sheet. Furthermore, in the laminated chip device, a through-hole is formed to penetrate each sheet, and the through-hole is filled with a conductor to connect the conductor patterns to each other in a vertical direction. Since the chip is manufactured by laminating and compressing the plurality sheets, a stress is accumulated in a region in which the through-hole is formed and particularly in a region in which the through-holes overlap with each other to result in deformation of the conductor in the through-hole, thus causing a distance between the conductor and the conductor pattern adjacent thereto to become smaller than the distance as originally designed. Thus, the laminated chip device fails to implement designed characteristics properly, and in the case where the conductor in the through-hole is severely deformed, the electricity is locally concentrated to cause occurrence of a short circuit, a leakage current, or a transient current.